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NITE STATES OHAUNCEY R. STUNTZ, OF TERRACE PARK, AND ALFRED A. OLERKE, OF GIN OINNATI, OHIO; HELENA G. OLERKE AND WILLIAM E. JONES (EXEOUTORS OF ALFRED A. OLERKE, DECEASED) ASSIGNORS TO SAID OHAUNOEY R.

STUNTZ.

SCHOOL-SLATE.

SPECIFICATION forming part of Letters Patent No. 358,581, dated March 1, 1887.

Application filed September 1, 1884. Serial No. 142,024. (ModcL) To all whom it may concern.-

Be it known that we, CHAUNOEY R. STUNTZ and ALFRED A. GLERKE, both citizens of the United States, and residents, respectively, of

Terrace Park, and Cincinnati, in the county of Hamilton and State of Ohio, have invented certain new and useful Improvements in School- Slates, of which the following is a specification.

Ourinvention relates to an improved method of permanently ruling, lettering, or otherwise ornamenting slates.

Heretofore slates have been ruled byscratching or cutting lines on their surfaces by means ofa sharp-pointed instrument. The indented linesproduced in this manner become faint and are obliterated in a comparatively short time, being filled with dirt and becoming as dark as the material composing the body of the slate, so that in writing a continued strain is imposed on the eyes of the children using them. These scratched lines or furrows are also 0bjectio11able,as they mar the beauty of the writing by causing an abrupt stop or break in each 2 long downstroke of the pencil,at the same time tending to weary the fingers of the writer.

The object of the indented or scratched line method has been to furnish positive checks and guides, whereby the children could learn 0 to write uniformly; but this is objectionable, because when a child has accustomed or trained himself to using a slate having such furrowed lines the writing becomes mechanical, and the sense of touch is depended on almost entirely,

instead of the sense of sight.

To remedy these defects is the object of this invention,which consists in ruling a slate with fixed indelible lines of any suitable color that may be easily seen, and that leave no break 0 or irregularity in the surface thereof.

To carry our invention into effect we rule the surface of the slate with a solution that will sink into or penetrate its pores, and that will produce either on the body of the slate itself a colored precipitate, or that can be pre 5 cipitated by another solution. In our process blue lines are produced by ruling first with solution of ferrous sulphate, followed by prussiate of potash. Yellow lines are produced by zinc solution followed by chromate ofpotash or chromate of potash followed by acetate of lead. The application of zinc solution followed by ammonic sulphide produces a grayish-white line,and the stronger acids also produce lines of a whitish hue.

It is obvious that any suitable instrument charged with the solutions or chemicals above described may be used to perform the work of ruling or otherwise designing the face of the slate and it is also obvious that slates may be ruled by any suitable coloring-matter that can be sunk into their surfaces or precipitated in their pores.

We claim 'As a new article of manufacture, a school- 55 slate made of argillaceous slate, having indelible lines,letters,or other marks produced within its surface by the chemical combination of an adjunct with the aluminum of its said substance, substantially as described.

In testimony whereof we have hereunto set our hands.

CHAUNOEY R. STUNTZ. ALFRED A. OLERKE.

Witnesses:

JOHN E. Jones, 0. L. J ONES. 

